patch from chinmaygarde@ to make progress on mac, ios.

build/toolchain/mac/BUILD.gn

Index: build/toolchain/mac/BUILD.gn
diff --git a/build/toolchain/mac/BUILD.gn b/build/toolchain/mac/BUILD.gn
index 237f6416cbf5ab7198259ec02ddb1c5ca28713cc..b2052d108d98a3cf87ab6e32c0546f2016008773 100644
--- a/build/toolchain/mac/BUILD.gn
+++ b/build/toolchain/mac/BUILD.gn
@@ -7,11 +7,13 @@
 # Linux.
 
 import("../goma.gni")
+import("//build/config/ios/ios_sdk.gni")
 
 assert(host_os == "mac")
 
 import("//build/toolchain/clang.gni")
 import("//build/toolchain/goma.gni")
+import("//build/config/sysroot.gni")
 
 if (use_goma) {
   goma_prefix = "$goma_dir/gomacc "
@@ -36,6 +38,8 @@ template("mac_toolchain") {
            "mac_toolchain() must specify a \"toolchain_cpu\"")
     assert(defined(invoker.toolchain_os),
            "mac_toolchain() must specify a \"toolchain_os\"")
+    assert(defined(invoker.switch_sysroot),
+           "mac_toolchain() must specify a \"switch_sysroot\"")
 
     # We can't do string interpolation ($ in strings) on things with dots in
     # them. To allow us to use $cc below, for example, we create copies of
@@ -48,9 +52,23 @@ template("mac_toolchain") {
     lib_switch = "-l"
     lib_dir_switch = "-L"
 
+    sysroot_flags = ""
+
+    if (invoker.switch_sysroot) {
+      version_flags = ""
+
+      if (use_ios_simulator) {
+        version_flags = "-mios-simulator-version-min=$ios_deployment_target"

[brettw, 2015/08/04 18:07:29]

I wonder if this can be more like Linux?

There we have a config "//build/config/linux:sdk" that gets added by default in
BUILDCONFIG.gn to all binary targets. That sets up the sysroot and related flags
when necessary.

This use of the sysroot variable is also not quite right. The toolchain
definitions are executed in the context of the default toolchain, so this might
not always refer to the thing you want. Using the above pattern will do the
right thing.

[Dirk Pranke, 2015/08/04 18:27:15]

I will add a comment and investigate that in a separate CL if that's okay?

[brettw, 2015/08/04 19:20:23]

This current one is definitely wrong so I'd rather not add the sysroot_flags
stuff which just needs to get deleted later. If you want to simplify this
change, I'd move this whole file's changes to a different CL.

[Dirk Pranke, 2015/08/04 19:28:06]

Okay, I'll see what I can do, one way or another.

+      } else {
+        version_flags = "-miphoneos-version-min=$ios_deployment_target"
+      }
+
+      sysroot_flags = "-isysroot $sysroot $version_flags"
+    }
+
     tool("cc") {
       depfile = "{{output}}.d"
-      command = "$cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_c}} -c {{source}} -o {{output}}"
+      command = "$cc -MMD -MF $depfile {{defines}} {{include_dirs}} $sysroot_flags {{cflags}} {{cflags_c}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "CC {{output}}"
       outputs = [
@@ -60,7 +78,7 @@ template("mac_toolchain") {
 
     tool("cxx") {
       depfile = "{{output}}.d"
-      command = "$cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}} -c {{source}} -o {{output}}"
+      command = "$cxx -MMD -MF $depfile {{defines}} {{include_dirs}} $sysroot_flags {{cflags}} {{cflags_cc}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "CXX {{output}}"
       outputs = [
@@ -81,7 +99,7 @@ template("mac_toolchain") {
 
     tool("objc") {
       depfile = "{{output}}.d"
-      command = "$cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_objc}} -c {{source}} -o {{output}}"
+      command = "$cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_c}} {{cflags_objc}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "OBJC {{output}}"
       outputs = [
@@ -91,7 +109,7 @@ template("mac_toolchain") {
 
     tool("objcxx") {
       depfile = "{{output}}.d"
-      command = "$cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_objcc}} -c {{source}} -o {{output}}"
+      command = "$cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}} {{cflags_objcc}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "OBJCXX {{output}}"
       outputs = [
@@ -125,7 +143,7 @@ template("mac_toolchain") {
       temporary_tocname = dylib + ".tmp"
 
       does_reexport_command = "[ ! -e $dylib -o ! -e $tocname ] || otool -l $dylib | grep -q LC_REEXPORT_DYLIB"
-      link_command = "$ld -shared {{ldflags}} -o $dylib -Wl,-filelist,$rspfile {{solibs}} {{libs}}"
+      link_command = "$ld -shared $sysroot_flags {{ldflags}} -o $dylib -Wl,-filelist,$rspfile {{solibs}} {{libs}}"
       replace_command = "if ! cmp -s $temporary_tocname $tocname; then mv $temporary_tocname $tocname"
       extract_toc_command = "{ otool -l $dylib | grep LC_ID_DYLIB -A 5; nm -gP $dylib | cut -f1-2 -d' ' | grep -v U\$\$; true; }"
 
@@ -160,7 +178,7 @@ template("mac_toolchain") {
     tool("link") {
       outfile = "{{root_out_dir}}/{{target_output_name}}{{output_extension}}"
       rspfile = "$outfile.rsp"
-      command = "$ld {{ldflags}} -o $outfile -Wl,-filelist,$rspfile {{solibs}} {{libs}}"
+      command = "$ld $sysroot_flags {{ldflags}} -o $outfile -Wl,-filelist,$rspfile {{solibs}} {{libs}}"
       description = "LINK $outfile"
       rspfile_content = "{{inputs_newline}}"
       outputs = [
@@ -202,6 +220,23 @@ mac_toolchain("clang_arm") {
   cxx = "${goma_prefix}$prefix/clang++"
   ld = cxx
   is_clang = true
+  switch_sysroot = false
+}
+
+mac_toolchain("ios_clang_arm") {
+  # TODO(GYP): Do we need ios_clang_armv7 and ios_clang_arm64 ?
+  toolchain_cpu = "arm"
+  toolchain_os = "mac"
+
+  # TODO(GYP): We need to support being able to use the version of clang
+  # shipped w/ XCode instead of the one pulled from upstream.
+  prefix = rebase_path("//third_party/llvm-build/Release+Asserts/bin",
+                       root_build_dir)
+  cc = "${goma_prefix}$prefix/clang"
+  cxx = "${goma_prefix}$prefix/clang++"
+  ld = cxx
+  is_clang = true
+  switch_sysroot = true
 }
 
 mac_toolchain("arm") {
@@ -211,6 +246,7 @@ mac_toolchain("arm") {
   cxx = "${goma_prefix}/g++"
   ld = cxx
   is_clang = false
+  switch_sysroot = false
 }
 
 mac_toolchain("clang_x64") {
@@ -222,6 +258,7 @@ mac_toolchain("clang_x64") {
   cxx = "${goma_prefix}$prefix/clang++"
   ld = cxx
   is_clang = true
+  switch_sysroot = false
 }
 
 mac_toolchain("x64") {
@@ -231,4 +268,5 @@ mac_toolchain("x64") {
   cxx = "${goma_prefix}/g++"
   ld = cxx
   is_clang = false
+  switch_sysroot = false
 }